Evaporator having refrigerant recirculation means



Feb. 22, 1949.

'H. G. MOJONNIER I EVAPORATOR HAVING REFRIGERANT RECIRGULA'I'ION MEANS 7Filed Jan. 12, 1945 3 Sheets-Sheet 2 IN V EN TOR. fid/rry lfoj'arziz'eflM aw/w e 9- H. G. MOJONNIER 2,462,329

EVAPORATOR HAVING REFRIGERANT REGIRCULATION MEANS Filed Jan. 12, 1945 3Sheets-Sheet 3 Patented Feb. 2, 19 49 UNITED STATES PATENT OFFICEEVAPORATOR HAVING REFRIGERANT RECIRCULATION MEANS Harry G. Mojonnier,Oak Park, Ill. Application January 12, 1945, Serial No. 572,527

Claims.

This invention relates to refrigerating apparatus, and particularly tocooler or evaporator structures and cooling methods used in conlunctiohtherewith.

It is an object of the invention to provide improved cooling apparatus,particularly adapted for use in refrigeration systems intended for thecooling of fluids, such as liquids and gases, and wherein the fluids tobe cooled may be circulated throug thecooling apparatus during thecooling processes.

More specifically stated, it is an object of the invention to providemeans of the type stated, which are more efficient in operation,providing a maximum cooling of the medium to be cooled with the use of aminimum of refrigerant, while further providing accurate temperaturecontrol and uniformity of operation.

A further object of the invention is to provide an evaporator or coolerunit, of the refrigerant flooded type, which is of compact and improvedconstruction, providing a maximum area and etficien'cy of thermalcontact between the refrigerant and the medium to be cooled, in respectto the size of the unit, and improved provisions for sanitation.

A still further object of the invention is to providean improved coolerstructure wherein the refrigerant and the'medium to be cooled, while inthermal or. heat transfer contact, are subjected to counter-flow inrespect to each other while the refrlgerantis continuously maintained ina condition facilitating a maximum absorption of heat from the cooledmedium.

Another obiect of the invention is to provide a cooler or evaporatorstructure of the flooded type,

wherein return of liquid refrigerant from the evaporator to thecompressor is precluded or minimized, as may be required.

Various other objects, advantages and features of the invention will beapparent from the following specification, when taken in connection withthe accompanying drawings, wherein certain preferred embodiments are setforth for purposes of illustration.

In the drawings, wherein like reference numerals refer to like partsthroughout:

Fig. 1 is a general layout, diagrammatic in form, are" refrigeratingsystem incorporating a cooler or evaporator unit,'constructed inaccordance with and embodying the principles of the invention; i

Fig. 2 is view; on an enlarged scale, partly in side elevation andpartly in section, of the evaporefrigerating apparatus,

or evaporator of the invention as arranged to effeet the cooling and gascharging of a liquid; a Fig. 6 is a plan view of the apparatus of Fig.5; Fig. 7 is a detail view generally similar to Fig. 2,

15 but showing the evaporator as embodied in the structures of Figs. 5and 6 and taken as indicated by the line 1-1 of Fig. 6; and

Fig. 8 is a view generally similar to Fig. 4, but

showing a cooling unit in the modified form of evaporator of Figs. 5, 6and '1.

Referring first to the embodiment illustrated in Figs. 1, 2, 3 and 4, inFig. 1 there is shown, diagrammatically, a refrigerating apparatusincorporating the evaporator or cooling unit of the invention. As shown,the apparatus comprises a compressor or ice machine In driven from asuitable source of power, such as an electric motor ii, The compressedgaseous refrigerant, which may for example be ammonia or Freon, istrans-.

mitted by means of a pipe or conduit I! to a condenser, diagrammaticallyindicated at l3. In the condenser the refrigerant is condensed intoliquid form, and transmitted by means of a conduit M to an injectorstructure l5, later to be described, by means of which it is introducedinto the cooler or evaporator, generally indicated by the numeral IS.

The fluid or liquid to be cooled is introduced into the evaporator bymeans of a supply pipe l8,

40 under control of an inlet valve l9. Within the evaporator therefrigerant medium and the fluid medium to be cooled are subjected tothermal contact, in a manner more specifically to be described, and aheat exchange takes place, as will be understood. The cooled fluid orliquid is suitably exhausted from the evaporator through an exhaust pipe20. The refrigerant, transformed into a gaseous state within theevaporator, is exhausted therefrom through an exhaust line 2| undercontrol of a back pressure regulating valve 22, being returned to thecompressor for recirculation through a return line 23.

The details and construction of the cooler or evaporator unit it areillustrated in Figs. 2, 3

and 4. ;The unit comprises an outer cylindrical 3 metal shell or coverplate 25, and an inner cylindrical metal shell 25, between which isinterposeda wall of insulating material 21 such, for example, as cork orthe like. The shell 26 is secured at its upper end, as by welding or thelike, to a tube sheet 28, and at its lower end to a tube sheet 28,whereby to form a cylindrical tank-like structure into which therefrigerant is adapted to be introduced, as will be described. The outercover shell embraces these tube sheets and extends therebetween. I

Disposed somewhat above the lower tube sheet 29, and in spaced relationthereto, is a separating baille wall and tube sheet 20. This baffle wallextends completely across the tank interior, being secured to the innershell 25, as by welding or the like, whereby to provide within the tank,an upper refrigerant chamber 3| and a lower refrigerant chamber 22, thechambers being separated by said baille wall 20.

A series of pipes or tubes 25 are arranged within the structure, beinganchored, respectively, at their upper and lower ends within the tubesheets 28 and 29. The baille wall tube sheet 30 carries a series oftubes 38, slightly larger than the tubes 25, and arranged in concentricrelation thereto. The tubes 26, in the particular embodiment shown, areunsupported at their upper ends, opening directly into the upperrefrigerant chamber 2|. If desired, the upper tube ends could besupported from the tubes 35, or from a tube sheet or spider, similar tothe tube sheet 20.

The detailed manner in which the tubes are supported by the tube sheetsis best illustrated in Fig. 4. As shown, the tubes may be expanded, asindicated at I] and 28 into annular recesses provided, respectively,in-the tube sheets 28 and 29 whereby to hold the tubes firmly inposition. It is to be understood, however, that various other suitablesecuring means may be employed. The tubes 36 may, for example, be weldedto the baffle wall tube sheet 20, or other suitable securing means maybe provided. It will be seen that due to .the difl'erence in size of thetubes, and the concentric disposition thereof, annular spaces orpassages 40 are formed between the tubes, these passages communicatingat their upper ends with the upper refrigerant chamber 3!, and at theirlower ends with the lower refrigerant chamber 32.

A head member 42 of dome-like shape is provided at the upper end of thestructure, this head member forming with the tube sheet 28 an upper headchamber 43 into which the fluid medium to be cooled is introduced by theinlet pipe I8, which may, for example, be formed as an integral part ofthe dome-like head. A ring member 44 may be welded to the lower portionof the dome 42, and secured by a series of bolts 45 to the tube sheet28, a gasket 46 being interposed between the parts to provide afluid-tight connection. The ring 44 and bolts 45 thus form suitablemeans for securing the head 42 in position,

but obviously other suitable securing means may be employed.

At the lower end of the structure there is provided a dome-like head 48secured to the lower tube sheet 29 by a ring member 49 and a series ofbolts 52, in a manner similar to that described in reference to theupper head structure. The lower dome head 48, with the tube sheet 29,forms a lower chamber or reservoir 5| for the flllid medium to becooled, and communicating with the upper head chamber 43 through thetubes 35.

4 A portion of the outlet conduit 28 for the cooled fluid medium may beformed as an integral part of the lower head dome 48.

As best shown in Fig. 4, each of the tubes 25 is provided at its upperend with a cap member 53, this cap member being provided with a seriesof openings 54 of predetermined size for metering and controlling therate of fluid flow through the tubes 25 and between the upper and lowerchambers 42 and 5i, as will be later described.

For circulating the refrigerant between the upper and lower refrigerantchamber 2| and 22, and for injecting the liquid refrigerant from thecondenser into the evaporator unit, the injector structure i5 isprovided. Specifically the injector comprises a housing 56, bolted tothe evaporator shell by means of a series of bolts 51. The housing formsa chamber 58 communicating with the upper refrigerant chamber 3|, andwithin this chamber is an injector throat 58 arranged to transmit therefrigerant from the chamber 58 into the lower refrigerant chamber 32 ofthe evaporator. An injector nozzle 58 communicating with the refrigerantinlet pipe I 4 provides the power means for circulating the liquidrefrigerant through the injector throat 52, as well as for continuouslyinjecting replacement refrigerant liquid into the unit. The injectornozzle 60 will be of predetermined selected size, in accordance with thecooling capacity and requirements of the system. In operation, severaltimes as much liquid refrigerant circulates through the injector throat59, as is introduced through the injector nozzle 68.

The vaporized refrigerant, vaporized within the evaporator by reason ofthe heat transfer processes, is ejected from the evaporator through thepipe 2| from the upper part of the upper refrigerant chamber 3 I, undercontrol of the back pressure regulating valve 22. A baffle 62 isprovided, in association with the pipe 2!, for precluding inadvertentreturn of liquid refrigerant from the evaporator.

A pair of sight glasses 4! and 84 are provided in association,respectively, with the upper and lower refrigerant chambers if and 32,for observing conditions therein, and a thermometer or heat indicator 55is associated with the liquid body in the upper refrigerant chamber, fordetermining the thermal conditions in the system.

In operation, the fluid medium to be cooled is introduced into the upperhead chamber 42 from the inlet supply pipe I I. The upper tube sheet 28and the cap members 52 with their oriiices 54 form a distributorstructure for causing the fluid flow downwardly through the pipes 35 totake place uniformly .in respect to all of the tubes, and at apredetermined rate. Preferably this rate is so determined that the fluidor liquid to be cooled which may, for example, be water is transmittedin the form of a thin fllm downwardly along the walls of the tubes intothe lower head reservoir 5i, from which the cooled water is withdrawnthrough the outlet pipe 28.

The refrigerant, in liquid form, is transmitted to the evaporator bymeans of the refrigerant inlet pipe I4, and is introduced into theevaporator at a predetermined rate in accordance with the coolingcapacity of the system, by the predetermined size injector nozzle 80.The action of the injector nozzle also produces a circulation of liquidrefrigerant, in a volume greater than that introduced through thenozzle, through the injector throat 59 and between the upper and lowerrefrigerant chamber 3i and 22. In passing from the chamber 32 to thechamber 3|, the liquid refrigerant passes upwardly through the tubes 36,and through the annular passages 40 in embracing relation to the watertubes 35, a heat exchange between the refrigerant and the water or otherliquid or fluid to be cooled taking place. At the upper end of the tubes36 the liquid refrigerant overflows into the chamber 3|. In normaloperation the liquid level of refrigerant within the chamber 3| may bemaintained, for example, approximately at the line A-A, as indicated inFigs. 1 and 2, the liquid refrigerant being initially charged into theevaporator, and maintained by the injection of replacement refrigerantthrough the nozzle 60, at substantially this level. In the upper spaces3|" of the chamber 3| the gaseous refrigerant, vaporized by the heattransfer processes, is separated from the liquid, and returned to thecompressor through the outlet pipe 2| and back pressure regulating valve22. As earlier indicated, the baffle plate 62 prevents the liquidrefrigerant overflowing from the tubes 36 being inadvertentlytransmitted to the outlet pipe 2 l.

Particular attention is directed to the fact that whereas a body ofliquid refrigerant is maintained within the unit only to the level A-'A,or thereabouts, the concentric tube arrangement is such thatsubstantially the entire length of the water pipes 35 is immersed in andsubjected to the action of a bath of liquid refrigerant. Thisarrangement provides a maximum cooling capacity, in respect to the sizeof the unit, with a minimum of refrigerant. The use of smallerquantities of refrigerant reduces costs, and minimizes oil accumulationwithin the evaporator which may separate from the refrigerant in theoperation of the system. The refrigerant in contact with the heattransfer surfaces of the water tubes 35 is in continuous circulationturbulence, and movement, facilitating the heat transfer processes. Acompact flooded type cooling unit is provided of a maximum efficiency,and wherein temperatures may be uniformly controlled.

The distributor caps 53 provide for a down flow film of the water to becooled, along the walls of the tubes 35, whereas the injector provides acontinuous counter-flow film of liquid refrigerant upwardly along theouter surfaces of the tubes 35, facilitating a maximum heat transfer.Counter-flow of the water and refrigerant is preferred, and is readilyeffected in the structure provided. It is obvious, however, that themedium to be cooled may be propelled in any desired direction throughthe structure. The multiplicity of tubes provides a minimum pressuredrop for the refrigerant within the system. The relatively low liquidlevel within the chamber 3| insures an adequate gas separation space 3|,precluding the transmission of liquid refrigerant through the outletpipe 2|, or surging of liquid therethrough, under various operatingconditions as when the system is started or the like. The removableheads 42 and 48 permit ready access to the internal parts of the tankstructure contacted by the medium to be cooled, thus facilitatingcleaning.

In Figs. 5, 6, 7 and 8 an embodiment is illustrated wherein the cooleror evaporator is arranged as a part of a complete refrigeratingapparatus, and wherein during the cooling of the liquid medium to becooled, a simultaneous gas charging or carbonating of the liquid takesplace.

Referring to Figs. 5 and 6, the apparatus shown comprises a compressorIlla driven by an electric motor Ila through drive connections 18, andadapted to propel gaseous refrigerant by means of a pipe or conduit I2a,under control of a hand valve II, to a water cooled condenser l3a. Thecondensed liquid refrigerant is transmitted by means of a conduit Maunder control of a hand valve 12, and a solenoid valve 13 automaticallyopened when the motor Ila is energized, to the injector |5a by means ofwhich the refrigerant is injected into the evaporator IBa as in thestructure previously described. The vaporized refrigerant is returnedfrom the cooling unit by means of a pipe 2|, a under control of a backpressure control valve 22a, and then returning by means of a return line23a and a hand control valve 14, back to the suction side of thecompressor.

The fluid medium to be cooled, which may in this instance be water mixedwith flavoring syrup, is supplied from a conduit 15 to a pump 16 drivenby an electric motor ll. From the pump the liquid is transmitted bymeans of a pipe |8a and check valve 18 into the upper dome head 42a ofthe cooling unit. Within the evaporator, the water is cooled in themanner previously described, passing from the lower head dome 48a oftheevaporator by means of an outlet pipe 2lla to a storage tank 19, fromwhich it may be drawn as desired by means of an out- 4 let pipe undercontrol of a-valve 8|. In the particular embodiment shown the cooledwater discharge pipe has associated therewith a safety blow-01f valve82, for a purpose presently to be described, there also being a sightglass 83 asociated with the discharge water pipe to observe the flow ofliquid therethrough.

An electric control unit or switch 85, controlled by the liquid levelwithin the reservoir tank 19, and arranged to control the operation ofthe pump motor 11, may be provided so as to start the pump motorwhenever the liquid level within the tank 19 drops below a predeterminedamount.

The reservoir tank 19 may be drained, as required, by means of a drainvalve 81. A drain valve 88 is associated with the lower reservoirchamber 32a within the evaporator unit, for draining accumulated oilseparating from the refrigerant within the evaporator unit. Apressureequalizing line 89 connects the top of the tank 19 with the lower headchamber of the evaporator, to facilitate proper flow through the drainline 20a.

In the present embodiment, means is provided for carbonating the syrupwater, with air or carbon dioxide gas, simultaneously with the coolingthereof. To this end a supply line 88 is provided leading from asuitable source of carbon dioxide gas pressure. A pressure regulator 9|reduces the gas pressure to a predetermined value, after which the gaspasses through a shut off control valve 92 through a line 93 into thelower head chamber of the evaporator unit, as best shown in Figs. 5 and'7. Within the evaporator it will be seen that the gas may pass upwardlythrough the tubes 35a, Figs. '7 and 8, into t e upper head chamber 43a.the cap members 53a in this instance being provided with upstanding pipeportions 95 communicating with the upper part of the upper head chamberso that the gas pressure, or flow of gas, may not interfere with thedown flow of the syrup water through the cap orifices 54a.

The operation of the structure of Figs. 5, 6, 7

and 8 is believed to be clear from what has heretofore been stated,sumce to say that in this instance, as the syrup and water mixture iscooled by down flow through the tubes a, embraced by the liquidrefrigerant, the water is simultaneously subjected to a carbonatingprocess by the carbon dioxide gas pressure within the tubes Ila andwithin the upper and lower head cham bers a and ila, so that as thesyrup water is discharged through the drain line a into the storage tank19, it will comprise a carbonated beverage liquid. The safety valve 82provides a safety pressure relief, in the event of abnormal pressureswithin the evaporator unit. a

As is obvious, the structure may be employed to carbonate syrup water,plain water, or other medium to be treated.

Referring further to Fig. 5, preferably the temperature indicator 65aincludes a thermostatically controlled switch in the control circuit forthe pump motor 11, so as to stop the pump if the evaporator temperaturedrops below or goes above predetermined limits. Proper cooling is thusinsured. When temperatures are too low, ice may form on the tubes 35a,forming an insulating wall resulting in improper cooling.

As best shown in Fig. 5, the upper head chamber may be provided with anindicator or pressure gauge 91, and with a purge valve 98. which may bemanually opened from time to time, as may be required. As will beunderstood, the other manually operable valves in the system, such asthe valves 1|, 11, 14, ill and 92 are normally open, with the exceptionof drain valves 81 and 8| which are normally closed.

It is obvious that various changes may be made in the specificembodiments set forth for purposes of illustration without departingfrom the spirit of the invention. For example, the water or other mediumto be cooled could be circulated through the unit in a plurality ofpasses or, the structure could be adapted for horizontal asdistinguished from vertical positioning. Accordingly the invention isnot to be limited to the specific embodiments shown and described, butonly as indicated in the following claims.

The invention is hereby claimed as follows:

1. An evaporator for use with refrigerating apparatus comprising a tankstructure, a pair of elongated tube members within the tank structure,said tube members being of different size, means for supporting thesmaller tube within the larger tube, means forming a gas and liquidrefrigerant separator chamber within the tank structure, meansinterconnected with said chamber for transmitting a refrigerant mediumthrough one of said tubes, said refrigerant transmitting means includingmeans for individually withdrawing gas and liquid phases of therefrigerant from said separator chamber, and means for transmitting amedium to be cooled through the other tube, whereby the wall surfaces ofthe smaller tube constitute a heat transfer surface engaged by therefrigerant medium and the medium to be cooled to eil'ect an exchange ofheat therebetween..

2. An evaporator for use with refrigerating apparatus comprising a tankstructure, a mind elongated tube members within the tank structure, saidtube members being of different size, means for supporting the smallertube within the larger tube, means forming a gas and liquid refrigerantseparator chamber within the tank structure, means interconnected withsaid chamber for transmitting a refrigerant medium through one of saidtubes, said refrigerant transmitting means including means forindividually withdrawing Ill and liquid phases of the refrigerant fromsaid separator chamber, means for transmitting a medium to be cooledthrough the other tube, whereby the-wall surfaces of the smaller tubeconstitute a heat transfer surface engaged by the refrigerant medium andthe medium to be cooled to effect an exchange of heat therebetween. andflow restricting means for restricting the flow of the medium throughthe smaller tube so that said medium forms a film on the inner surfaceof said tube.

3. An evaporator ,for use with refrigerating apparatus comprising a tankstructure, a pair of elongated tube members within the tank structure,said tube members being of different diameter, means for supporting thesmaller tube within the larger tube, means forming a gas and liquidrefrigerant separator chamber within the tank structure, means forindividually withdrawing gas and liquid phases of a refrigerant mediumfrom said separator chamber and for circulating theliquid phase of therefrigerant medium from said chamber through one of the tubes, and meansfor transmitting a. medium to be cooled through the other tube, wherebythe wall surfaces of the smaller tube constitute a heat transfer surfaceengaged by the recirculating refrigerant medium and the medium to becooled to effect an exchange of heat therebetween.

4. An evaporator for use with refrigerating apparatus comprising a tankstructure, a pair of elongated tube members within the tank structure,said tube members being of different diameter, means for supporting thesmaller tube within the larger tube, means forming a gas and liquidrefrigerant separator chamber within the tank structure, meansinterconnected with said chamber for individually withdrawing gas andliquid phases of a refrigerant medium from said separator chamber andfor transmitting the liquid phase of the refrigerant medium through oneof said tubes in one direction, and means for transmitting a medium tobe cooled through the other tube in the opposite direction, whereby thewall surfaces of the smaller tube constitute a heat transfer surfaceengaged by the oppositely flowing refrigerant medium and medium to becooled to effect an exchange of heat therebetween.

5. An evaporator for use with refrigerating apparatus comprising a tankstructure, a first set of elongated passages extending through the tankstructure, a second set of elongated passages extending through the tankstructure, the individual passages of said sets being in thermalcontact, means forming a gas and liquid refrigerant separator chamberwithin the tank structure, means interconnected with said chamber forindividually withdrawing gas and liquid phases of a refrigerant mediumfrom said separator chamber and for transmitting the liquid phase of therefrigerant medium through one of said sets of passages, and means fortransmitting a medium to be cooled through the other set of passages,whereby to effect an exchange of heat between the refrigerant medium andthe medium to be cooled as said mediums are transmitted through saidsets of passages in thermal contact.

6. An evaporator for use with refrigerating apparatus comprising a tankstructure, a first set of elongated passages extending through the tankstructure, a second set of elongated passages extending through the tankstructure. the individual passages of said sets being in thermalcontact, means forming a gas and liquid refrigerant separator chamberwithin the tank structure, means for individually withdrawing gas andliquid phases of a refrigerant medium from said separatorgchamber andfor recirculating the liquid phase of the refrigerant medium from saidchamber through one of said sets of passages, and means for transmittinga medium to be cooled through the other set of passages, whereby toeffect an exchange of heat between the recirculating refrigerant mediumand the medium to be cooled as they are transmitted through said sets ofpassages in thermal contact.

'7. An evaporator for use with refrigerating apparatus comprising a tankstructure, a first set of elongated passages extending through the tankstructure, a second set of elongated passages extending through the tankstructure, the individual passages of said sets being in thermalcontact, means forming a gas and liquid refrigerant separator chamberWithin the tank structure, means interconnected with said chamber forindividually withdrawing gas and liquid phases of a refrigerant mediumfrom said separator chamber and for transmitting the liquid phase of therefrigerant medium through one of said sets of passages in onedirection, and means for transmitting a medium to be cooled through theother set of passages in the opposite direction, whereby to effect anexchange of heat between the refrigerant medium and the medium to becooled.

8. An evaporator for use with refrigerating apparatus comprising a tankstructure, a reservoir forming a gas liquid separator for refrigerantformed within said tank structure, means for individually withdrawingthe gas and liquid phases of the refrigerant from said reservoir tothereby maintain a predetermined liquid level of refrigerant within saidreservoir, a first set of elongated passages extending through the tankstructure, said passages being in communication with said reservoir butbeing of greater longitudinal extent within the tank structure than theliquid body in said reservoir, a second set of elongated passagesextending through the tank structure, the individual passages of saidsets being in thermal contact, said withdrawing means including meansfor circulating refrigerant between said reservoir and said first set ofelongated passages, and means for transmitting a medium to be cooledthrough said second set of passages, whereby to effect an exchange ofheat between the refrigerant medium and the medium to be cooled.

9. An evaporator as defined in claim 8, wherein said refrigerantwithdrawing means includes an injector structure.

10. An evaporator for use with refrigerating apparatus comprising a tankstructure, a reservoir forming a gas liquid separator for refrigerantformed within said tank structure, means for individually withdrawingthe gas and liquid phases of the refrigerant from said reservoir tothereby maintain a predetermined liquid level of refrigerant Within saidreservoir, a first set of elongated tubes extending through the tankstructure, said tubes being in communication with said reservoir butbeing of greater length within the tank structure than the liquid bodyin said reservoir, a second set of elongated tubes extending through thetank structure, the tubes of one of said sets being smaller than thetubes of the other set and being supported therewithin, said withdrawingmeans including means for circulating refrigerant between said reservoirand said first set of tubes, and means for transmitting a medium to becooled through said second set of tubes, whereby to effect an exchangeof heat between the refrigerant medium and the medium to be cooled.

11. An evaporator as defined in claim 10, wherein said refrigerantwithdrawing means comprises an injector structure for circulating theliquid phase of the refrigerant.

12. An evaporator for use with refrigerating apparatus comprising a tankstructure, a head chamber formed at one end of said tank structure, ahead chamber formed at the other end of said tank structure, a set oftubes extending between said head chambers and communicating therewith,a fluid reservoir disposed within said tank structure extendinglongitudinally thereof between said head chambers, individual outletsleading from said reservoir adjacent its opposite longitudinal ends, aset of tubes communicating with said reservoir, the tubes of one of saidsets being smaller than the tubes of the other set and beingrespectively disposed therewithin, and means for transmitting a re-'frigerant medium through one of said sets of tubes and for transmittinga medium to be cooled through the other sets of tubes, whereby to effectan exchange of heat therebetween, said refrigerant transmitting meansincluding means for individually withdrawing gas and liquid phases ofthe refrigerant from the individual outlets of said reservoir. a

13. An evaporator for use with refrigerating apparatus comprising a tankstructure, a head chamber formed at one end of said tank structure, ahead chamber formed at the other end of said tank structure, a set ofvertically disposed tubes extending between said head chambers andcommunicating therewith, a pair of fluid reservoirs disposed within saidtank structure between said head chambers, one of said reservoirs beingelongated longitudinally of the tank and forming a gas and liquidseparator for refrigerant, a set of tubes communicating with saidreservoirs, said first named set of tubes being smaller than the lastnamed set of tubes and being respectively disposed therewithin, andmeans for transmitting a refrigerant medium through the larger set oftubes and for transmitting the medium to be cooled through the smallerset of tubes, whereby to effect an exchange of heat therebetween, saidrefrigerant transmitting means including means for individuallywithdrawing gas and liquid phases of the refrigerant from said elongatedreservoir.

14, An evaporator for use with refrigerating apparatus comprising a tankstructure, a head chamber formed at one end of said tank structure, ahead chamber formed at the other end of said tank structure, a set ofvertically disposed tubes extending between said head chambers andcommunicating therewith, a pair of superposed fluid reservoirs disposedwithin said tank structure between said head chambers, one of saidreservoirs being elongated longitudinally of the tank and havingindividual outlets at the opposite longitudinal ends thereof, saidreservoir forming a separator for gas and liquid refrigerant, a set oftubes communicating at their ends respectively with said reservoirs, thetubes of said last named set being larger than the tubes of the firstnamed set and being respectively in embracing relation therewith, meansfor withdrawing refrigerant gas from one of said outlets and fortransmitting refrigerant liquid 11 between the reservoirs through saidother outlet whereby to maintain liquid refrigerant within the lower ofsaid reservoirs and to a predetermined level within the upper of saidreservoirs and for circulating the refrigerant between said last namedoutlet.

HARRY G. MOJONNIER 12 ammcas 01mm The following references are of recordin the file of this patent:

UNITED STATIB PATENTS Number Name -Da tc 2,058,907 Phiiipp Oct. 27, 19362,063,646 Whitesel Doc. 8. 1936 10 2,233,059 Miller Feb. 25, 19412,387,899 Gruner Oct. 30, 1945

